Mr. 2 Bon Clay: Psycopath

After unlocking all 14 characters, including Shanks, Mihawk, Chopper, and Ms. Sunday, type in this code during the credits after beating the game with sanji again: (L)+ A, A, X, A, Left, A, X, B, A, X, Y, X, A, R, R, Left.

New Title Screen

Unlock all the characters to reveal a new title screen that features everyone.

Unlock Mihawk

Clear Event Battle with Zoro on Hardest difficulty. Beat Mihawk with Zoro's level 2 special after getting hit with Mihawk's level 2 special. You must unlock all other character before this including Enel, Aokiji, and Shanks.

Unlock Shanks

Clear Event Battle with Luffy on the Very Hard difficulty after unlocking all previous characters including Enel and Aokiji.

Unlock Enel

After clearing event battle with Luffy, Zoro, Nami, Usopp, Sanji, Chopper, and Robin complete some of there move lists in training mode. A picture should flash by of Enel challanging you, go to Grand Tours (tournament mode) and just play a regular tournament, one of the characters will be replaced with Enel, beat Enel and win the tournament to unlock Enel.

Unlocking Straw Hat Pirate's 4th Costumes

At the Start Screen, hold (R) and input these codes for the 4th costumes. You will hear a ding if done correctly.

Up, X, Up, X, B, A, A, Up   Luffy's 4th Costume
Left, X, Left, X, Y, Y, B, Down  Nami's 4th Costume
Down, X, Down, X, B, A, A, Y  Zolo's 4th Costume
Up, X, Down, X, Y, B, Y, X  Sanji's 4th Costume
Right, X, Right, X, A, Y, B, X  Usopp's 4th Costume
Left, A, Right, X, Y, Left, Right, B  Chopper's 4th Costume

Unlockable Characters

Foxy: Clear Event Battle twice with Chopper.  
Bon Clay: Clear Event Battle with Chopper.  
Sir Crocodile: Clear Event Battle with Robin.  
Smoker: Clear Event Battle with Luffy.  
Don Krieg: Clear Event Battle with Sanji.  
Arlong: Clear Event Battle with Nami.  
Buggy: Clear Event Battle with Zoro.  
Kuro: Clear Event Battle with Usopp.